The C‐5A is designed to provide the capability to transport heavy logistics payloads and outsize military equipment over long ranges for the lowest possible system and operating costs. It provides airport performance and traffic speeds equal to or better than current transports and is capable of operation into and out of short unprepared fields. A general arrangement drawing is shown in Fig. 1. The overall length is 246 ft., the wing span is 222 ft., and the overall height is 65 ft. Of the many missions which the C‐5A must perform, those critical to the design are shown in Tables I and II. The first of these largely defines the high lift system requirements for take‐off and climb performance, the second and third missions dictate the maximum take‐off gross weight for a limit load factor of 2.5 g, and the fourth mission defines the maximum take‐off gross weight for a limit load factor of .25 g. The support area landing distance requirement furnishes an additional constraint on the design of the high lift system. The C‐5A is designed to provide flotation characteristics that will permit 130 take‐offs and 130 landings using short unprepared fields having a California Bearing Ratio of 9. To achieve this flotation a total of 28 wheels, 24 of which form the main landing gear, are used. Stowage provisions for the landing gear constituted a substantial challenge to the aerodynamicist to devise fairings which minimized the penalty which conventional design would accrue. The C‐5A provides the capability of both nose and tail straight in loading at truck bed height in order to achieve a turnaround time of 15 minutes. In addition, it is capable of air dropping both cargo and personnel. These capabilities dictated the use of an upswept aft fuselage which provides clearance for straight in loading. The static ground clearance angle of 10 deg. comfortably exceeds the 7.75 deg. used for lift‐off: the ground clearance angle available with the gear kneeled to place the cargo floor at truck bed height is 7.4 deg. while the maximum ground clearance angle with the gear fully extended is 11.75 deg. The upsweep, or inverse camber, of the aft fuselage introduced the possibility for excessive drag due to the loss of pressure recovery or flow separation in this area. The development of the fuselage configuration to avoid this problem will be discussed in later paragraphs.
Paterson, J. (1968), "Aerodynamic Design Features of the C‐5A: An account of some of the problems encountered and the solutions adopted in the design of the Galaxy", Aircraft Engineering and Aerospace Technology, Vol. 40 No. 6, pp. 8-15. https://doi.org/10.1108/eb034383Download as .RIS
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